1. Field of the Invention
This invention relates to an image forming apparatus such as a printer, a copying apparatus or a facsimile apparatus and a unit such as a process cartridge detachably attachable to the main body of the image forming apparatus.
2. Related Background Art
In recent years, various interchangeable units having semiconductor memories attached thereto have been proposed for the purpose of improving the quality of image of copying apparatuses, printers, etc. and the accurate custody of the service life of the units. For example, in Japanese Patent Application Laid-Open No. 8-160680, it is described to attach a semiconductor memory to a process cartridge detachably attachable to an electrophotographic type printer.
The process cartridge disclosed in the above-mentioned publication comprises a photosensitive drum, a charging device, a developing device and a cleaner made into a unit easily detachably attachable to an image forming apparatus of the electrophotographic type. Also the storing means of the above-described process cartridge is a semiconductive non-volatile memory in which the cumulative rotation time of the photosensitive drum is stored to detect the service life of the photosensitive drum.
Now, in the above-described apparatus, the nonvolatile memory and the main body of the image forming apparatus have been connected by a connector.
However, the signal to the memory is weak and even a slightly bad contact of the connector causes malfunctioning.
So, it has been suggested to connect the main body of the image forming apparatus and the memory together by electromagnetic coupling means, and effect bilateral communication through the electromagnetic. coupling means mechanically in non-contact to thereby avoid bad contact of the connector.
In the electromagnetic coupling, however, electromagnetic waves may leak from the coupling portion. Also, with regard to these electromagnetic waves leaking from the apparatus, the intensity thereof must be reduced to a predetermined limit by the international standard. Further, extraneous noise may jump into the coupling portion to thereby cause malfunctioning.
The present invention has been made in view of the above-described problems and an object thereof is to provide an image forming apparatus which can suppress the outward Leakage of electromagnetic waves from the communication position between the main body of the image forming apparatus and a detachably attachable unit, and a unit detachably attachable to this apparatus.
Another object of the present invention is to provide an image forming apparatus in which the communication position can be smoothly shielded when a unit is attached to the main body of the image forming apparatus, and a unit detachably attachable to this apparatus.
Still another object of the present invention is to provide an image forming apparatus having a main assembly, a unit having a memory and a first antenna electrically connected to the memory, the unit being detachably attachable to the main assembly, communication means having a second antenna and for communicating with the memory when the unit is mounted on the main assembly, and electrically conductive shield means surrounding at least the first antenna and the second antenna when the unit is mounted on the main assembly.
Yet still another object of the present invention is to provide a unit detachably attachable to an image forming apparatus, the unit having a memory, an antenna electrically connected to the memory, and an electrically conductive member disposed between a main body of the unit and the antenna.
Further objects of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.